1991 Chevy Truck rear end yoke

This is going to sound stupid to you but there is a torque but it is not really specific. If you tighten the yoke to tight then you mess with the proload on the pinion bearings and it will wear them out prematurely. So it's best to just kin dof tighten it back up and keep turning the yoke so it doesn't turn to tight. It is a locking nut so it won't back off or shouldn't anyhow. If you have changed the pinion seal then you have to take the end play out as well. Hope this explains it.